There is provided a mobile communication system, a base station, and a method of controlling cell coverage that is capable of operating a mobile communication system such that the cell coverage is maintained approximately and timely at a target level without requiring much labor. In this mobile communication system, a mobile station reports to the base station the position information of the mobile station and the value of reception power of reference signal from the base station. The base station obtains the measured cell coverage as a result of measurement of cell coverage based on the position information and the value of reception power from the mobile stations, and controls at least one of plural parameters including transmission power to the mobile stations, tilt angle of antenna, etc., so as to minimize deviation of the measured cell coverage from the target cell coverage.